1. Field of the Invention
The present invention relates to the formation of metal-filled patterns in semiconductor wafer fabrication. More particularly, the present invention relates to the formation of a diamond metal-filled patterns achieving low parasitic coupling capacitance.
2. Description of the Related Art
In recent years, chemical-mechanical polishing (CMP) has become the primary technique for planarizing interlayer dielectrics. Although CMP is effective at planarization, CMP processes are hampered by layout pattern sensitivities which cause certain regions on a chip to have thicker dielectric layers than other regions due to differences in the underlying topography. This problem has become particularly severe as performance requirements have increased, dimensions have scaled, and larger die sizes have appeared. CMP has also been widely used in VLSI technology development as a tool for creating shallow trench isolation and in damascene processes.
In order to reduce layout pattern dependent dielectric thickness variation, the layout pattern itself is changed via the introduction of metal-fill patterning. Metal-fill patterning is the process of filling the large open areas on each metal layer with a metal pattern, which is either grounded or left floating, to compensate for pattern-driven variations. Unfortunately, due to the confidential nature of metal-fill patterning practices and design rules, relatively little information about metal-fill patterning practices has been available to the public.
In addition to reducing layout pattern dependent dielectric thickness variation, metal-fill patterning practice should also minimize the parasitic capacitance associated with the metal-fill. However, conventional metal-fill generally introduces a substantial amount of parasitic capacitance due to capacitance between the metal-fill and metal lines of the integrated circuit formed on an integrated circuit substrate. In view of the above, it would be beneficial if metal-fill patterning with reduced parasitic coupling capacitance could be achieved.